Field of Invention
Various exemplary embodiments relate generally to an electronic device and, more particularly, to a controller controlling a semiconductor memory device and an operating method thereof.
Description of Related Art
Semiconductor memory devices are made of semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (Inp). Semiconductor memory devices are classified into volatile memory devices and non-volatile memory devices.
Volatile memory devices lose stored data when powered off. Examples of volatile memory devices include Static RAM (SRAM), Dynamic RAM (DRAM) and Synchronous DRAM (SDRAM). Non-volatile memory devices retain stored data regardless of power on/off conditions. Examples of non-volatile memory include Read Only Memory (ROM), Mask ROM (MROM), Programmable ROM (PROM), Erasable Programmable ROM (EPROM), Electrically Erasable and Programmable ROM (EEPROM) flash memory, Phase-change Random Access Memory (PRAM), Magnetic RAM (MRAM), Resistive RAM (RRAM) and Ferroelectric RAM (FRAM). Flash memories are classified into NOR-type memories and NAND-type memories.
A semiconductor memory device controller may generate commands at the request of a host and perform the generated commands. The controller may include a command queue to store commands. The command queue may be defined in a memory unit such as a RAM. Commands stored in the command queue may be sequentially output to the semiconductor memory device.